Telephone metering system



0a. 14, 1930. A. E.'HAGUE 1,778,319

TELEPHONE METERING SYSTEM Filed June 7, 1929 4 SheetsSheet l l 4/NVEN7'0/? A. E. HA GUE ATTORNFV Oct. 14, 1930.- A. :E. HAGUE 1,778,319

TELEPHONE METERING SYSTEM Filed June 7, 19/29 4 Sheets-Sheet 2} IIHI'I 0Q a; m & fa F, E: E Q E Q w R {I- N B QL L QR I N N INVENTOR A.E.YHAGUE" ATTORNEY Oct. 14, 1930. HAGUE 1,778,319

TELEPHONE METERING SYSTEM Filed June 7', 1929 4 Sheets-Sheet 3A.E.HAGLIJE By Oct. 14, 1930.- A. E. HAGUE 1,778,319

TELEPHONE METERING SYSTEM Fil ed June 7, 1929 4 Sheets-Sheet 4 llll llllINVENTOR A. E. HAGUE Patented Oct. 14, 1930 UNITED STATES PATENT OFFICEALFRED E. HAGUE, OF WEST ORANGE, NEW JERSEY, ASSIGNOR TO BELL TELEPHONELABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEWYORK TELEPHONE IMETERING SYSTEM Application filed June 7, 1929. SerialNo. 389,028.

This invention relates to dial telephone eX- change systems andparticularly to metering arrangements applicable to party lines.

' It has for its object economy in the amount of equipment necessary forsuch metering.

In accordance with one embodiment of the present invention means isprovided com mon to a plurality of district selectors for testing thecalling line to determine the calling substation and-to establish arecord in the district selector of that substation. Severalidentification circuits are provided each normally serving a singlegroupof district selectors, but capable, should one or more of them fail tofunction properly, of serving more than one group of selectors. A timingarrangement is provided and means for dis criminating whether a delay isdue to faults in the identification circuit or in the district selectorand in response to such discrimination to release the district selectoror to con nect it with a different identification circuit. l he testingof the line involves reversal. of current flow over the line. In orderto reduce the clicks produced by this reversal a network is provided ineach identification circuit. This network is connected in parallel withtie talking circuit by the same operation that associates the districtselector with the identification circuit after which the talking circuitis opened and the network thereby inserted therein. The network remainsin position during the performance of the tests and until after the linehas been reclosed.

The invention will be more clearly understood from a consideration ofthe following: description in connection with the attached drawings inwhich Fig. 1 shows a portion of a district selector; Fig. 2 showsfourparty line, an individual line, and the common meter controlequipment; Fig. 3 shows one complete party identification circuit; Fig.4 shows portions of two other identification circuits; and Fig. 5 is adiagram indicat an idle sender and the wanted line number is recorded inthe sender which thereupon controls the selective operations of thedistrict selector nd other switches. lVhen selections have beencompleted a relay is operated which connects an idle identificationcircuit with the calling line. The operation of this relay connects anetwork in parallel with a section of the talking circuit as it extendsthrough the district selector and then opens the talking circuit toinsert the network therein. The identification circuit then connects arelay to both sides of the line in parallel to detern'iine whether thesubstation. calling is grounded and then in effect applies battery firstto one side of the line and then to the other to operate the polarizedrelay at the substation which, by its response, de ermines theregistration. Following the reg stration the line is reclosed and theidentification circuit is disconnected from the selector. lVhen thecalled subscriber answers and the charge relay operates as an indicationthat the call has been successful, a meter control circuit is associatedwith the district selector under the control of the registration set upby the identification circuit. The meters of the corresponding party ofall lines located on the same frame are connected to the respectivemeteringterminals of the line. For example, if the calling substationwere substation #1, then the :ttl meter for c cry party line appearingin the same panel would be connected to the metering terminal of thecorrespondin ine. Thisoperation i i pplica o ring curl terr .al for ameasured inte"- val after which the current is *ovcd and t'.. cr controlci t selector.

l y 100, thus initiating the op- These eration of a trio, start and linkcircuit. circuits in turn bring about the operation of a particular linefinder and district selector for the purpose of extending the call. Theline finder, for example line finder 101, counects with the callingline, after which The the line is associated with a sender.

mt to lower back-contact of relay 105, upper contact of relay 112, toground at the baclr 'eloses'a. circuit tron operation of the dial on thecalling line registers the number of the wanted subscriber in the senderin accordance with which the sender controls the operation of thedistrict selector 102 and other switching apparatus for completing theconnection. The sequence of operations of the district selector isguided by a sequence switch which advances from position to position asthe circuit functions. Since the foregoing operations are merelyincidental to the present invention, no attempt has been inade to eithershow or describe the apparatus and its functions in detail. Reference ishereby made to U. S. Patent 1,589,402, granted January 22, 1926 to G. H.Kopp, for a detailed description of the establishment of'a connectionthrough equipment of the type shown. 7

As set forth in the above identified patent, the operations of the lineinder 101 and districtrselect-or 102 take place in positions 1 to 9inclusive of the sequence switch while those of the switching apparatusto which the district selector has access, take place with the districtselector sequence switch in position 10. When the selections havecompleted, indica't-ion'of this is returned to the sender which advancesthe district selector sequence switch fromposi-uion 10 to position 12.As soon as the sequence switch leaves position 10, a circuit is closedfrom ling of relay. 103,

battery, through the w i lower contacts of sequence switch cam 10 1,baci;

contact of relay 300. This circuit also e tends to ground at the backcontact of relays 400 and 150 so thatshould relay 300 b e.op eratedbecause of a failure of the identification circuit, as will he describedhereinafter, relay 103 will nevertheless be operated. Re

lay 103 looks over its lower front contact and the back cont-act ofrelay 112 to ground at the back contact of relay 300, thus'renderingitself independen of the sequence switch and of relay 105. relay 103 ino iiere.

ba zteiyiv throng sf its upper frontcontact, lower winding of relay 303,lo"er back contact of contact, inner back contact of of the dist 'ictsequence switch selections and conversation .while' 'the identificationis being made. itelays 106and 107 complete connections from 106,lowerback contact of relay 801, lower back contact'of'relay 302, to ingo r i.-

ground. Relay 1 06 operates, '1 its upper winding and over its inding ofrelay 30%, upper back relay 302 to ground. per contact of relay 106 alsocompletes a circuit in parallel with the upper winding of relay 106 forrelay 10?,which also opera s after an interval. Relays 106. and 107' areheld operated independent of the position so that tall:- may proceed andthe district selector as well scribers line are uninte The 01681110111the upthe identification circuit to the district selector. The fouruppermost contacts of relay 107 serve to connect network 310 in parallelwith a portion of the talking circuit, namely, that part passing throughthe contacts of relay 105. These circuits may be traced: From the tipbrush of the line finder, fourth contact of relay 107, upperback contactof relay 800 to the upper right terminal of the network, through theupper retardation coil, uppermost back contact of relay 311 upper backcontact of relay 307, sixth contact of relay 107, to the tip conducuorof the talking circuit at a point beyond the Contact of relay 105; 'romthe ring brush of the line finder, third contact of relay 107, innerback contact of relay 306, to the lower right terminal of the network810, lower retardation coil, middle back contact of relay 311, throughthe winding of relay 312, inner back contact relay 307,'upper normalcontact of relay 316,

lower winding of relay 315, upper back contact of relay 307, sixthcontact of relay 10?, upper back contact of relay 109, upper leftindingfof repeating coil 108 to ground.

Relay 315 o ierates in this circuit and initiates the testing of thecalling line. operat on of relay 815 completes. a circuit from ground atits upper front contact, inner back Contact of relay 309, middle lowerfrontcontact of relay 106, upper wading of relay 105 to batoc Relay 105operates, opening thetalking circuit atits contacts andthiis introducingthe network 310 into thetalking circuit so that the subsequent tests mayproduce no unpleasant clicks or ther noises to 0 disturb theconversation. ll the inclusion of'the network in theta hing circuit y isincludedin a :ircuitfed by battery through the repeating coil 108 andextQ-EK ng over the subscribers line, in which circuit relay 312operates provided the cone ductors connecting the identification circuitThe closure of'the locking circuitof relay 106 causes the opei iion ofrelay 301 which in turn operates relay 301; to prevent the transfer ofthe call to another, identification circuit. RelayBOl also closesacircuit over its lower front contact, lower baclrcontact of relay313,windingof relay 314 to batt ry, preparing a timing circuit fordetermining whether tie tests are completed properly. It also connectsground Over conductor 32 to the armature of relay 312. V j

1:30 7 The Assuming that relay 312 operates, a circuit is closed frombattery, through the winding of relay 313, lowermost back contact ofrelay 311, contact of interrupter 317, front contact of relay 312 togrounded conductor 320. Relay 313 looks through the winding of relay311, over the upper front contact of relay 313 to grounded conductor320. Re ay 311 does not operate until interrupter 317 opens its contactto open the shunt around the winding of relay 311. lVhen relay 311operates the subscribers line is disconnected. from the repeating coil,but relay 315 remains bridged across the repeating coil holding theconnection. The two sides of the subscribers line are then extended overthe upper front contacts of relay 311 and the back contacts of role 318to the winding of relay 319 and battery, to determine whether thecalling party is one identified by ground.

Examining Fig. 2 for a moment it will be apparent that each party 210,220, 230 and 240 has a polarized relay and a grounded contact associatedwith the substation. ith the receiver removed from the switchhook thesubstations 210 and 220 are not grounded while substations 230 and 240have ground connected through the winding of the polarized relay to theline. In the case of substation 230 the ground extends over an auxiliaryContact of the switchhook, back contact of pole i/ied relay 231,retardation coil 232, upper winding of polarized relay 231, through theswitchhook, transmitter and dial contacts 236 to the ring conductor, andthrough both windings of the polarized relay and one winding of thesubstation repeati coil to the tip conductor. In the case of n 21-0 theground extends over the a V co: act of the switchhook, back contact'ofre y 2 11', retardation coil 242, upper winding of relay 241,,leftWinding of coil 24:4: to the ti conductor while it extends through bo hw VllllflfS of the polarized relay throu 'lie switchhook, transmitterand dial contacts the ring conductor. Since the subscriber at substation220 was assumed to be calling, ground will not be connected. to eithertip or rip; conductor and relay 319 will not be operated. It should benoted that the battery connected to relay 319 is the re verse of thatused el ewhere so that it has no effect on. the polarized at thesubstations.

The nest closure of the contact of intcrrupter 317 completes a circuitIrom grounded conductor 320, middle front Contact of relay 313, Contactof interrupter 31?, lower tcontact of elay 311, back contact of relay321, lower back contact of relay 322,

winding of relay 318 to battery. Relay 318 operates and loclzs throughthe winding of relay 322 and the lower front contact of relay 318 togrounded conductor 320 but relay 322 d esnot operate until interrupter317 opens its contact. lVhcn ground was connected to conductor 320 acircuit was also closed over the lower back contact of relay 318 to thewinding of relay 326 and battery. Therefore, the operation of relay 318extends the tip conductor of the subscribers line over the front contactof relay 311, front contact of relay 318, back contact of relay 322, tothe upper winding of relay 323 and battery and in parallel throughresistance 341 and the inner upper front contact of relay 326 to bat- Italso extends the ring conductor over the middle -front contact of relay311, inner upper front contact of relay 318, inner upper back contact ofrelay 322, through the lower winding of relay 323, to battery throughlamp 324 and in parallel with the winding; of relay 323, throughresistance 3 1-2 and the up per front contact of relay 326. Battery 325the usual coin battery and has a value of approximately 110 volts whilethe battery connected to the upper winding of relay 323 approximately 50volts. The net result of the use of these two batteries is the same asthough one 50 to 60 volt battery were con nected to the side of the lineto which the coin battery is connected. The purpose served by using thetwo batteries will be apparent hereinafter. The operation of relay 318opens the circuit of relay 326 which is slow to release and, therefore,after a short interval opens the shunts closed through its contactsaround the windings of relay This, therefore, permits the polarized.relay in the substation to operate, if it is going to, before relay 323becomes effective. In the present case polarized relay 221 operatessince it is so connected and polarized as to respond to negative batteryapplied to th ringconductor. When relay 221 operates it connects groundover the auxiliary switchhook contact, front contact of relay 221,through retard coil 222, upper winding" of relay 221, contact 226,trmismit-ter 225, dial contact 224: to the ring; conductor. It alsoconnects ground over the switchboard contact, front contacts of relay221, retardation coil. 222, both windings of polarized relay 221,winding of repeating coil 227 to the tip conductor. Therefore, whenrelay 32o relcases opening the shunts around the windings of relay thisground imbalances the circuit of differential relay 323 so that therelay opcrates and closes a circuit from ground, over its front contact,inner back contact of relay 308, innermost lower front contact of re 1y108, winding of relay 109 to battery. Relay 109 operates and locks oversequence switch cam 110 to ground. It is to be noted that the windingsof relay 323 are so proportioned that the current flowing through themfrom 110 volt battery 325, over a loop at the subscribers substation, tocentral oflice battery connected to the upper winding of relay 323maintains the relay unoperated whereas with ground connected. to thecircuit at the-sub station, the current through one winding is reversedand results in the operation of the relayf The same holds true of relay327;

At the same time that relay 326 was operateda circuit was closed frombattery, through the winding of relay 328, inner lower back contact ofrelay 322 to grounded conductor 320. Therefore, when relay 322 operatesfollowing the openin of the contact of interrupter 317, the tipconductor of the calling line is extended over the-outer upper frontcontacts of relays 311, 318 and 322,'the upper winding of relay 327, andin parallel therewith through resistance 3 13 and the upper frontcontact of relay 323,,through lamp 324 to 110 volt battery 325. The ringconductor is extended over the inner upper contacts of relays 311,318and 322 to central ofiice battery through the lower winding of relay 327and in parallel therewith through resistance 34 1 and the inner frontcontact of relay 327 to central ofiice battery. As in the case. of relay323 relay 327 cannot operate with its windings shunted in this manner-QThe operation-of relay 322 opens the circuit of relay 328 and whenthisrelay releases after an interval the w ndin s of relay.;327 are connected 'dlrectly to the line. Since the polarized-relay221 responds onlyto battery over A the ring conductor, it does not operate at thistime-and, therefore, does not connect ground 2 to the line,'leavingrelay 327 unoperated.

" The next closure of the. contact of interrupter 317 completes acircuit from conductor 32-0, front contact of relay 313, contact ofinterrupter 317, innermost front contact of relay 311, back contact ofrelay 321, lower most front'contact of relay- 322, winding of relay 316-to bat-tery. Relay 316 operates and locks to conductor 320. Italsoconnects ground from conductor 320, over its innermost lower contact tothe winding of relay of relay 316 to grounded conduct-or 320. Theoperation of relay 312 opens the locking circuit'of relay 315 and theoperation of relay 316 connects resistance 329 in parallel with theoperating winding of relay 315, thus releasing relay 315. The release ofrelay 315 opens the circuit of relay 105 and that relay releasesrestoring the talking circuit to its "normal condition. The releaseofrelay 315 also opens the circuit of relay'314. The reclosure of thetalking circuit shunts the winding of relay 312-which now releases. Acircuitis-now closed frombattery, through resistance'lll, winding ofrelay 112, lowermost front. contact ofrelay 106, upper back contact ofrelay 309, unoer back contact of relay 315, innermost front contact ofrelay 313, back contact of relay 312 to grounded conductor 320. Relay112 looks over its inner upper front contact to ground over cam 110. Theoperation of relay 112 opens the locking circuit of relay 103 and thatrelay releases in turn releasing relays 106 and 107, followed by relay304. The release of'relay 304 disconnects ground from conductor 320,thus releasing relays 313, 316, 318, 322 and 301.

hen the called subscriber answers polar- 'zed relay 113 operates in thewell known manner. A circuit is thereupon completed from ground, overcams 11 1 and 115, front contact of relay 113, cam 116, left contact ofinterrupter 117, winding of relay 118 to battery. Relay 118 operates andlocks over cams 119 and 116, front contact of relay 113, cams 115 and1141 to ground. When interrupter 117 closes its right-hand contact acircuit is closed from ground as previously traced, over the inner upperfront contact of relay 118, cam 120, winding of relay 121 to battery.Relay 121 locks over its upper front contact and cams 115 and 114 toground. I

At the conclusion of the conversation relay 113 releases in turnreleasing relay 118, thus intitiating the restoration of the line finderand district selector.

In the meantime with relays 121'a-nd 112 operated a circuit is closedfrom battery, over the lower front contact of relay 121, inner lowerfront contact ofrelay 112, upper winding of-relay 122, winding of relay250, back contact of relay 251, back contact of relay 252 to ground,assuming that the meter con trol circuit is idle. Relay 250 operatesmomentarily, but relay 122 looks through its lower windin and frontcontact to the winding'of relay 252 which operates opening theenergizing circuit for allrelays such as relay 122 and releasingrelay250. Relay 252 also closes a circuit from ground, through its frontcontact, winding of relay 251 to battery. Relay 251 operates and closesa circuit from ground at the front contact of relay 252. inner leftfront contact of relay 251, middle upper front contact of relay 122,alternate contact of relay 109, since relay 109 was operated as abovedescribed, lowermost back contact of relays 123 and 124, winding ofrelay 253 to battery. Relay253 is one'of four party relays each 'ofwhichis individual to one of the four parties connected to. a party line. Forexample, relay 253 is individual to the secondparty and relay 237 isindividual to the third party. The line finder and district selector ofFig. 1 is arranged to serve a maximum offour hundred lines. As willappear hereinafter theselines may be either individual lines or partylines; Ifall of the lines served by'this line finder are party lines, itis necessary that each party relay prepare cirlines appear on the sameline finder frame with party lines, the corresponding contacts of themulti-contact relays need not be equipped. The operation of relay 253,therefore, by operating the multi-contact relays 25-1, 255, etc,prepares circuits for all of the second party meters belonging to theparty lines served by the district selector of F 1. The operation ofrelays 255 and 25% closes a circuit from ground, over their right frontcontacts, right back contact of relay 256, right back contact of relay257, winding of relay 258 to battery. Relay 255 also prepares a circuitfrom ground through the winding of message register 223, outer leftfront contact of relay 255, back contact of line relay 100 (which is nowdeenergized having been released by the operation of cut-off relay 125when the line was found in the well known manner), to the meteringterminal 126 of the calling line. The circuit may be further traced overthe line finder brush, uppermost front contact of relay 122, inner rightfront contact of relay 258, Winding of relay 259 to battery. Relay 259operates for a purpose which will be described hereinafter. Theoperation of relay 258 also closes a circuit from battery, through thewinning of relay 260, middle front contact of relay 258, left contact ofinterrupter 261. When interrupter 261 closes this circuit relay 260perates, locking over its inner front contact to ground at the frontcontact of relay 252. When interrupter 261 closes its right contact itcompletes a circuit from ground, over the outer front contact of relay260, innermost upper front contact of relay 122, resistance 111 andbattery. This shunts the winding of relay 112 and that relay releasesopening the circuit of relay 122 in turn releasing relay 252, andrestoring the meter control circuit to normal. Since the operatingcircuit of relay 112 was closed through the contact of relay 106, whichis now released, it is i1npossible to make a second charge irrespectiveof the length of the conversation, although it is obvious that there isnothing in the present inventive idea which would prevent its adaptationto repeated charging under the control of the proper equipment.

Had the subscriber at substation 230 been calling the removal of hisreceiver would have connected ground over contact 238, back contact ofrelay 231, retardation coil 232, upper winding of relay 231, switchhookcontact 234, transmitter 235, dial contact 236 to the ring conductor andthrough both windings of relay 231, left winding of the repeating coilto thetip conductor.- When, therefore, relay 319 is connected to the tipand ring conductors as above described this relay operates.

Relay 319 in operating closes a circuit from ground through the windingof relay 321, contact of relay 319, upper back contact of relay 305,innermost contact of relay 107, through the winding of relay 12 1 tobattery. Battery through resistance 330 is connected in parallel withrelay 124, thus insuring the operation of relay 321. hen relay 12 1operates and locks over its inner-upper front contact and the bottomcontact of cam 110, this locking ground is connected in shunt ofresistance 330 and battery, releasing relay lVith relay 321 operated theinterrupted ground controlled by interrupter 317 is transferred from thewinding of relay 318 to the winding of relay 316 so that if relay 12stdoes not operate before the next closure of interrupter 317, theidentification circuit will be dismissed and no registration willbe setup in the district, resulting in a free call.

If the registration is made correctly the remaining tests are made asabove described. Relay 231 is polarized to respond to battery connectedto the ring conductor. Therefore, when relay 318 operates connectingbattery 325 to the ring conductor, relay 231 operates disconnecting theground at its back contact from the line. lVnen relay 326 rel asesopening the shunt around the winding of relay 323, the current flowthrough that relay prevents its operation. hen battery is connected tothe tip of the line by the operation of relay 322, relay 231 does notoperate and the ground remains connected to the line. Therefore, whenthe shunts are removed from relay 327, this ground causes the operationof relay 327 closing a circuit from ground, over the f ont contact ofrelay 327, upper back contac of relay 303, second front contact of relay107, winding of relay 123 to battery. Relay 123 loci-ts over i s innerupper front contact to the ct of cam 110. lVhen the re 'ation e ui mentfunctions the meter electing circuit may be traced from grourul, overthe outer right front contact of relay 256, inner left front contact ofrelay 251. middle upper front contact of relay 122, normal contact ofrelay 109, upper front contacts of relays 123 and 12%, winding of relay237 to battery. Relay 237 operates and connects the third party meter233 to the metering terminal of the line ready to receive meteringpotential as previously described.

In the case of substation 210, relay 211 responds to battery connectedto the tip conductor and conneccai ground over front contact to the lineoperating relay 327 and in turn relay 123. In the case of substation 240since the operation of the hook switch connects ground. to the line,relay 319 is operated in the manner described for substation 230 in turnoperating relay 12 1-. Relay 241 does not respond to heavy batteryconnected to the ring conductor and, thereregistration relays 124 and109 operate.

' of interrupter 261.

fore, the ground which remains connected to the line operates relay 323,in turn operating relay 109. Relay 241 does respond to battery connectedto the tip'conductor, and removes the normal ground therebyprevent' ingthe operation of relay 327.

To summarize i If substation 210 calls, registrat-ion relay 123operates. lfsubstation 220 calls registration relay-109 operates Ifsubstation 230 calls, registration relays '124 and 123 operate. Ifsubstation 240 calls.

Relay 109 serves the added purpose of reversing the direction of currentflow through the substation so that the ground will be removed from thel1ne during conversation. In the case ofsubstation' 220 it prevents theoperation of relay 221, while in the case of substa- 4 ual line will notbe provided with a polarized relay, grounded contact and a choke coilsuch as shown in connection with the party line. Since there is noground at any point of the test none of relays 109, 123 or 124 isoperated. The meter selecting circuit extends from ground over the frontcontact of relay 252, inner left front contact of relay 251, middlefront contact of relay 122, normal contact of relay 109, upper backcontact of relay 123, upper winding of relay 127, windings of relay 256to battery. Relay 256 operates and closes a circuit from battery,through the winding of relay 258, right back contact of relay 257, toground at the outer right front contact of relay256. It also closes acircuit from batte"y, through the winding of relay 259, in nor frontcontact of relay 258, uppermost contact of relay 122, to the meteringterminal of the individual. line, over the back contact 1 of messageregister 202 to ground. Relay also prepares a circuit from battery,through the winding of relay 260, middle front contact of relay 258, tothe left contact lVhen interrupter 261 closes that contact relay 260operates and locks to ground at the outer front contact of relay 258.Relay 260 prepares a circuit from ground, over the right contact ofinter- 1 rupter 261,outermost contact of relay of 260,

inner front contact of relay 122, to resistance 111 and battery, thusreleasing relay 1'12, and terminating the registration in the mannerpreviouslydescribed.

In order to discriminate between a lack of registration because the linetested is an individual line and one due 'to faulty opera tion of theidentification equipment, the winding of relay 127 is introduced in thecircult of relay 256 as above described. ff -the the line relay (notshown) and the wind-' line is an individual line the message registerwill be connected directly to the meteringtermin'al and relay 259 willoperate in series therewith. If the lack of registration is due tofaulty functioning relay 259 cannot operate. Therefore, when relay 260operates, battery is connected over-the back contact of relay'259,middle front contact of relay 260, in shunt of the highresistancewinding of relay 256, thus reducing the resistance in serieswith relay 127. Relay 127 is marginal-and cannot ope ate as long as thehigh resistance winding of relay 256 is in its circuit. lVith thiswinding shunted relay 12'? operates and closes a circuit over itslowermost contact, lowermost contact of relay 112, to the meter 123. Arecord is, therefore, set up ofthe number of imes that the equipmentfails to register. This meter is common to the district selectors servedby the identification equipment. If the number of failures recordedappears excessive, key 129 may be operated, locking relay 127 andflashing lamp 130 so that the identity of the district selector may bedetermined. Relay 127 also opens the circuit of down-drive magnet 131 ofthe line finder, preventing its restoration to normal and thusindicating the line with which the trouble arose.

Relay 106 is'individual .to the district selector and a similar relaysuch as relay 132, etc., is provided. for each district selector of thgroup served by the identification circuits of Figs. 3 and 4. Theserelays are arranged in sequence and the locking circuit of any relayextends over the back contacts of the relays following it in thesequence. Therefore, if two relays operate at the same time only thelower relay in the sequence can lock and the other district selectormust await the release of the identification circuit. If, for anyreason, this chain locking circuit is broken so that relay 106, forexample, cannot lock. the operation of relay 303 in the energizingcircuit of relay 106 prepares a circuit from ground, over the frontcontact of relays 303. right contact of interrupter 331, winding ofrelay 332 to battery. Relay 332 looks over its upper f ont contact tothe front contact'of relay 303. Relay 303' also closes a circuit from'ground, over its front contact,rlower contact of relay 313, winding ofrelay 314 to battery. If relay 106 looks through the winding of relay304 the circuit of relay 303 isopened at once and relay 332 cannotoperate. Vi ith relays 332 and 314 both operated the closure of the leftcontact of interrupter 331 completes a circuit from ground at the frontcontact of relay 303, left contact of interrupter 331., lower frontcontact of relay 332, front contact of relay 314, winding of relay 333to battery. Relay 333 locks through its lower winding and lower frontcontact, key 334, winding of relay 335 to ground, thus operating analarm which can only be silenced by the operation of key 33 1-. It alsolights lamp 336 to indicate which identification circuit failed. Relay333 also connects ground over its front contact, uppermost back contactof relay 309, lowermost contact of relay 100, which is operatedbut notlocked, winding of relay 112, resistance 111 to battery. Relay 112releases relays 103, 100 and 303. Since no registration was set up thecall will proceedasa free call. If relay 106 locks, relay 30% operatesin the locking circuit, opening the circuit of relay 303. However, relay30 1 substitutes ground at its lower front contact for the ground at thefront contact of relay 303. Therefore, if the line is open so that relay312 cannot operate, and in turn relay 313 does not operate, relay 31%remains operated and the alarm operates as above described.

According to the present disclosure three identification circuits areprovided to serve a large group of district selectors and each of thesenormally'serves a particular part of the group. Means has been provided,however, so that if one identification circuit fails to function, one ofthe other identifica tion circuits may be used. If the identificationdoes not take place within a predetermined time relay 332 is operatedunder the control of interrupter 331 and looks as above described. Theoperation of relay 313 releases relay 314- so that the subsequentclosure of the left contact of interrupter 331 extends ground over thefront contact of relay 332, back contact of relay 314, to lamp 337 andwinding of relay 300 and battery. Relay 300 extends its operating groundover the back contact of similar relays 100 and 450 of the otheridentification circuits, through the winding of relay 338, key 339,right winding of relay 340 to battery. Relays 338 and 3&0 operate, relay3 10 sounding an alarm and locking to the alarm circuit. The op erationof relay 333 connects ground over its front contact to the armature ofrelay 300, thus holding relay 300 operated When interrupter 331 opensits contact. Relay 300 also closes a circuit for relay 302. Relay 302opens the circuit of relay 3041 at its upper back contact and when relay301 releases completes a circuit over the upper front contact of relay302, back contact of relay 301, through the windings of relays 305, 306,307, 308 and 309 in parallel to battery. Relays to 309 in operatingtransfer the circuits which connect the district selector with thisidentification circuit to the identification circuit shown at the leftof Fig. 4. Since both identification circuits indicated on Fig. 4 areidentically the same as that shown in Fig. 3, only the transfer andswitching relays have been shown.

If the second identification circuit should fail to complete itsfunction in the proper time the same operations will take place and thecircuits further extended to the third identification circuit. In caseall three fail, the operation of relay 450 of the third identificationcir uit opens the circuit of relay 338 and releases relays 300, 400 and450. Calls may also be rerouted from the second identification circuitto the third and first and from the third identification circuit to thefirst and second in the same way as they were advanced from the first tothe third as above described.

If at the completion of the identification tests, relay 312 fails toreoperate and consequently relay 315 does not release, a circuit isclosed for relay 31 1, over the lower front contact of relay 315, outerlower front con tact of relay 316 to grounded conductor 320, thusoperating relay 338 and bringing in an alarm through the operation ofrelay 335. Relay 333 operates relay 112 as before.

It is to be noted that where the failure to make registration is theresult of trouble on the part of the line or the district selector,relay 112 is operated and the identification circuit merely dismissed.lVhere the difficulty is due to the identification circuit an attempt ismade to complete the identification by associating the district selectorwith other identification circuits.

lVhat is claimed is:

1. In a telephone exchange system, telephone lines, a plurality ofsubstations on said lines, a plurality of selectors, means for extendinga. connection from one of said lines over any one of said selectorsunder the control of one of said substations, and means common to saidselectors and said lines for identifying said substation.

2. In a telephone exchange system, a telephone line, a plurality ofsubstations on said line, a plurality of selectors, means for extendinga connection from said line over any one of said selectors under thecontrol of one of said substations, an identification circuit common tosaid selectors, means to associate said identification circuitindividual ly with a selector, and means in said identification circuitto set up a record in the selector of the identity of said substation.

3. In a telephone exchange system, a telephone line, a plurality ofsubstations on said line, a plurality of selectors, means for extendinga connection from said line over any one of said selectors under thecontrol of one of said substations, an identification circuit common tosaid selectors, means to a."- sociate said identification circuitindividnah ly with a selector, means in said identification circuit toset up a record of said substation in said selector, and means in saidselector responsive to the completion of identification to disconnectsaid identiii tion circuit from said selector.

4. In a telephone exchange system, a telephone line, a plurality ofsubstations on said to setup a record in the selector of saidsubstation, and means in said identification cir cuit eli'ective if saidselector is not in condition to receive the identification to disconnectsaididenttication circuit from said selector.

5. In a telephone exchange system, tel phone lines having a pluralityo-tsubscribers substations, a plurality of groups of selector switches forextendin connections from said lines, an identfication circuitcommon toeach group of selector switches, means in each identification circuit toidentify a calling substation and to set up a record of the substationinv a selector, and means effective if an identification circuit doesnot function pro perly to associate the identification circuit ofanother group with said selector.

6. In a telephone exchange system, telephone line, a plurality ofsubstations on said lines, certain of said substations being connectedto ground, a plurality of selectors, means for extending a connectionfrom said line over any one of said selectors under the control of oneof said substations, an identifi cation circuit common to saidselectors, means in said identification circuit to determine whether thecalling partys substation is con nected with ground and to record thatfact in said selector, and means effective if said record is notestablished to disconnect said identification circuit from saidselector.

7. In a telephone exchange systenna line having a plurality ofsubstations thereon, a plurality of selectors for extending connectionsover said line under the control of any one of said substations, meansto test said line to determine the substation controlling the extensionof the particular connection, a network common to said selectors, meansto insert said network-in the circuit of said line before testing saidline, and means responsive to the completion of the test to'remove saidnetwork from said line. 1

8. In a telephone exchange system, a line having a plurality ofsubstations thereon, a plurality of selectors for extending connectionsover said line under the control of any one of said substations, meansto test said line to determine the substation controlling the extensionof the particular connection, a net work common to said selectors, meansto connect said network in parallel with a portion of the circuit ofsaid line, means responsive to the establishment of said parallelconnection to open said line intermediate the terminals of said parallelconnection, means thereafter efiective to initiate said test, and meansresponsive to the completion ot-said test to reclose said line andthereafter disconnect said network from said line. 7

9. In a telephone exchange systenn'telephone lines having a plurality ofsubscribers substations located thereon, a plurality of selectorswitches for extending said lines, an identification circuit common tosaid selector switches, means responsive to the establishmentof aconnection over one of said selectors switches to set up a talkingcircuit through said selector, means also responsive to theestablishment of a connection to i361 porarily

